Rotor head



May 19, 1953 M. D. BUn/1D 2,638,994

ROTOR HEAD Filed March 30, 1951 2 Sheets-Sheet l INVENTOR MICHEL D. BUIVID ATTORNEY M. D. BUIVID May v19, 1953 ROTOR HEAD Filed March 30, 1951 2 Sheets-Sheet 2 INVENTOR MICHEL D. BUIVID BY/f. @TMW ATTORNEY Patented May 19, 1953 y NITITEDl L'OEFICE rMichel D. -Buivid, 'MilfordfGDIm-g =assignor-to United Aircraft Corporation, East Hartford, Conn.,y a corporation of Delaware `Application March 30, 1951," Serial 'No'.` 218,313

4 Claims. (Cl. Mre-1560,55)

movement :about generally horizontal flapping f hinges.

One of the difficulties encountered in aircraft of this type has'been a tendency to excessive wear in theflapping hinges of the separately articu- 'latedv blades due tolthe fact that centrifugal force acting on the .rotating blades causes the inboard Sides ofthe flapping hinge bearings to carry all of the bea-ring load while centrifugal force-actingcn the-lubricantin the bearings moves the lubricant to the outboardsides o-f the bearings.

Itis an object ofv this inventionvtoxprovide van improved (flapping hinge construction for the blades, .of .rotarywing aircraft in which the bearing-loads dueto centrifugal force. actingon the blades act on the outboard. sides of the 4flapping hinge bearings wherethereis always adequate lubricant.

Another object of theinvention is to provide an improved construction of iflappinghinge -for supporting the draghinge dampersofa `rotary Wing aircraft.

Afurther object. of this invention is lgenerally to. :improve the :z construction and prolong. 4the working'lifecf rotor heads for rotary .wing aircraft.

'ifhesefandotheriobjectsA and advantagescf the invention will become apparent-or vwill-be particularly pointed outin'the-following description of apreferred embodiment of the invention shown in the accompanying drawings:

L Inzthese drawings:

* Fig. 1 is a 'top plan View :of a :three-bladed'helicopter embodying the invention; 1 Fig. 2 isan enlarged View of aparty of the -rotor head of Fig. l showing the structure for attaching one of the blades,.-parts being shown in section in the vicinity of the flapping hinge;

Fig.' 3 isa side Yelevation ofli'ig. 2 withparts shown in section rto facilitate: illustration and,

Fig. 4. is a perspective detail of the drag hinge showing' the flapping hinge bearings.

-As herein shown, the helicopter .embodying the present invention includes an elongated fuselage .lwhich contains a forward pilot compartment i2 and a centrally disposed cargo or passenger compartment id above which a pylon I6 'supports a generally upright main drive shaft i5 which drives the rotor head generally indicated at 20. The engine for driving the roto-r is contained in a nose compartment 22 and the torque of the singlesmain-fmotcr is' compensated for-by a tail rUtOr-Mflocated-at the extremity of a tail-cone 2li extending aft-of, the fuselage.

i'Ifl'ie'main drifveshaft l5 carries a splined hub 32 havingfilangesrdwand A3li\vvl1-icl1 are bolted to corresponding spaced plates 38- and 40 as shown 'in Fig-3.

- Plate 140- has a `tubularJ depending extension I 8 to which "the scissors 1-91 which'v drives the rotating swashplatel 3Bis pivotally connected.

spaced plates andr L40 uwhich,l yasy shown in Fig. 3 have three radially extending arms: 32 as fshowncinFig:l 2. These arms-fare spaced 120 apart andproyide the support for the three articulated rotor` blades. 44. The fuppel extremity of the; drive Yshaft lvis provided-With a hoisting eye 46 which; is secured thereto :by a; threaded -rstud Min Vany suitable manner. Surrounding the stud '4.o is a fhollow can- :50. which cooperates Width: an opstanding'4 fiange;4 U512 plate 38. i The arms '42 are supported intermediate -their v `length' by spacers f5 41. which are held in f position by'. bolts 56 extended :thrcughthe spacers and fthe upper and lower plates 'and 14,0. "Each arm 42 of the upper andi-loweniplates 38 and'fd supports. an articulated vrotor. 'blade- M. fr. Since sthethree. blades and the ,frnountings'` therefon are identical; only `one has been` shownr indetail: rand only one will .be described herein. fAtthe extremities-the arms 42 havezvertically aligned apertures in which a' drag hinge fis-journalled onfneedlebearingstt and vS52 -inzplatesf-SS andli respectively. A ballthrust bearing e 53= y.is also i provided inl 'the somewhat heavier lower plate 40; the Whole bearing assembly -beingpositioned by upper and lower nuts G4-and 66 `.which are screw threaded onto the upper and lower` axial lends of the drag hinge. Suitablelclosure caps'/ 68. and` 'l0 `are provided above and belowplates 38 and '40 4to enclose the hinge bearings and to confine'the usual lubricant provided v'for the bearings.

As shown most-clearly in l'ig.` 4, the vertical hin-ge, or-vdraghingehas a transverse passage l2 the axisof which-intersects its own vertical axis. 'fThis-passagefhas two rollerY bearings 14 andl thereinon which is journalled a' flapping hinge Altfwhich is' xed in the forked ends 8i! of a napping link^82. As showrrmpst clearly in Fig. 2, the horizontal lnapping pini l"I8 'is provided with a replaceablebearing-sleeve84-Which isheld in position in the passage l2 by engagement with the confronting inner faces of the forked ends 8&3 of the flapping link. The pin 'I8 is clamped rigidly into the forked ends of the flapping link between a shoulder 86 and a clamping nut 88 on the pin so that rotation of the pin in the forked arms 80 is made impossible and all rotation of the flapping link relative to the drag hinge 58 takes place between the bearing sleeve 84 and the needle bea-rings 14 and 16 in the passage 12 of the drag hinge.

The blade 44 is attached to the flapping link 82 by means which provide for folding of the blade. To this end the flapping link has a radially extending feathering spindle I90 on which the blade attaching sleeve 92 is ournalled for rotation to vary the pitch of the blade. Inboard of the blade attaching sleeve 92 a blade pitch changing horn 94 -is also journalled on the spindle 90 and is normally connected withsleeve 92 by a slidable` looking pin 96. It will be evident that when the pin 96 is retracted from the boss 98 attached by iiange 93 to sleeve 92, the latter can then be rotated freely on the spindle 90 during the blade folding operation. However, when the pin 96 is engaged in the boss 98 movement of the blade pitch changing horn 94 will adjust the pitch of the blade about the axis of the spindle. Control of the blade pitch is obtained in. a usual manner through a push-pull rod which connects Via universal 95 to the horn. `91! and with the rotatable swashpla-te member 30 via universal 91. Tilting of the stationary swash-` plate member 28 is accomplished by means of usual push-pull rods, one of which is shown on 102, to impart cyclic pitch control to the blades of the rotor head.

Referring to Fig. 2, it will be noted that the horizontal hinge ypin 18 which is rigidly connected to the napping link has a laterally extending portion |04 on which a damper mounting sleeve |06 is journalled on taper bearings |08 and H0. Damper H2, which may be the usual hydraulic cylinder and piston type damper yshown in my Patent No. 2,554,774, issued May 29, 1951, is pivotally supported at I I4 on the end of sleeve |06, the Idamper being thus bodily movable with the flapping link as the latter moves about the rdrag hinge 58 in the plane of rotation of the blade. Furthermore this allows the blade to move in the iapping plane without aifecting the damper. The inboard end `of the piston rod IIB is connected by a suitable pivot joint H8 to the hub structure between the upper and lower plates 38 and 40 as' shown most clearly in Fig. 2 and carries the usual piston IIS at its free en'd.

As a result of the above described construction for hinging the flapping link in which the generally horizontal hinge pin for the flapping link is rigidly secured in this link and is journalled in hub-carried bearings, it will be evident that centrifugal forces acting on the blades will cause the bearing pressures due to these centrifugal loads to be exerted against the outboard side of the hub-carried bearings 16 where the lubricant for the bearings 'is naturally moved by the same centrifugal forces.

It will also be evident that a particularly Isimple and effective means has been provided for mounting the `drag hinge dampers on the ends of the flapping hinge by which flapping movements of the blades does not 'affect the dampers.

While the invention has been Ishown in connection with .a preferred form thereof, it will be evident that various changes in the construction and arrangement of the parts may be resorted to without ldeparting from the *scope 'of the invention.

I claim:

1. In a rotary Wing aircraft, a hub structure, a generally horizontal napping hinge pin journalled in said hub structure, a napping link secured rigidly to said pin 'and movable bodily therewith in said hub journal, vsaid pin having an extension on 'one side of said flapping link, a

sleeve journalled -on said extension, a 'damper` including cooperation piston 'and `cylinder elements, a pivotal connection between said sleeve and one of said damper elements, and a pivotal connection between the other damper element and said hub structure.

2. In a rotary Wing aircraft, a drive shaft, hub structure on said shaft including spaced upper and lower plate elements, a drag hinge journalled in said plate elements for movement about a generally vertical axis, a flapping hinge pin journalled in said drag hinge for movement :about a -generally horizontal axis, said pin extending laterally beyond said drag hinge on both sides of -said journal, a flapping link having a yoke strad- -dling said drag hinge and secured to said flapping pin -on opposite sides of said drag hinge, a sleeve journalled on one of the extensions of said flapping pin, a damper including cooperating piston and cylinder elements, a pivotal connection between one of said damper elements and said sleeve, and a pivotal connection between said hub structure and the other of said damper elements.

3. In a rotary wing aircraft, a hub structure, a rotor blade pivotally lconnected to said hub structure by iiapping and ldrag hinges, said flap ping hinge having a lateral extension, a sleeve journalled on said extension, "a damper for controlling movements of said blade about `said drag hinge having cooperating cylinder and piston elements, a pivotal connection between one of said damper elements and said sleeve, and a pivotal connection between the other damper element and said hub structure.

4. In a rotary wing aircraft, a hub structure, a drag hinge journalled in said hub structure for movement rabout a generally vertical axis, a flapping hinge pin journalled in said drag hinge for movement about a generally horizontal axis, said pin having its ends projecting laterally beyond said ydrag hinge on both sides vof said journal, a flapping link having a yoke on its inboard end straddling said drag hinge and secured to the extension of said flapping pin, a sleeve journalled on one of said extensions, a damper including lcooperating piston and cylinder velements having a pivotal connection between `one of said elements and said sleeve, and a pivotal connection between the other damper element `and said hub structure.

MICHEL D. BUIVID.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,948,456 Cierva Feb. 20, 1934 1,986,709 Breguet et al. Jan. 1, 1935 2,105,682 Bennett et al Jan. 18, 1938 2,529,635 Sikorsky Nov. 14, 1950 

